title: Bacillus thuringiensis: A story of a successful bioinsecticide.
abstract: Bacillus thuringiensis (Bt) bacteria are insect pathogens that rely on insecticidal pore forming proteins known as Cry and Cyt toxins to kill their insect larval hosts. At least four different non-structurally related families of proteins form the Cry toxin group of toxins. The expression of certain Cry toxins in transgenic crops has contributed to an efficient control of insect pests resulting in a significant reduction in chemical insecticide use. The mode of action of the three domain Cry toxin family involves sequential interaction of these toxins with several insect midgut proteins facilitating the formation of a pre-pore oligomer structure and subsequent membrane insertion that leads to the killing of midgut insect cells by osmotic shock. In this manuscript we review recent progress in understanding the mode of action of this family of proteins in lepidopteran, dipteran and coleopteran insects. Interestingly, similar Cry-binding proteins have been identified in the three insect orders, as cadherin, aminopeptidase-N and alkaline phosphatase suggesting a conserved mode of action. Also, recent data on insect responses to Cry toxin attack is discussed. Finally, we review the different Bt based products, including transgenic crops, that are currently used in agriculture.
authors.affiliation: Instituto de Biotecnología, Universidad Nacional Autónoma de México, Apdo. Postal 510-3, Cuernavaca 62250, Morelos, Mexico.
authors.forename: Alejandra
authors.initials: A
authors.lastname: Bravo
authors.forename: Supaporn
authors.initials: S
authors.lastname: Likitvivatanavong
authors.forename: Sarjeet S
authors.initials: SS
authors.lastname: Gill
authors.forename: Mario
authors.initials: M
authors.lastname: Soberón
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D001413:Bacillus thuringiensis / Q000737:chemistry / Q000378:metabolism / Q000472:pathogenicity; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism / Q000633:toxicity; D018826:CD13 Antigens / Q000378:metabolism; D015820:Cadherins / Q000378:metabolism; D019476:Insect Proteins / Q000378:metabolism*; D007313:Insecta / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D007306:Insecticides; D008958:Models, Molecular; D010572:Pest Control, Biological / Q000379:methods*; D030821:Plants, Genetically Modified; D052899:Pore Forming Cytotoxic Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism / Q000633:toxicity; D011485:Protein Binding
chemical_list: D001426:Bacterial Proteins; D015820:Cadherins; D019476:Insect Proteins; D007306:Insecticides; D052899:Pore Forming Cytotoxic Proteins; D000469:Alkaline Phosphatase; D018826:CD13 Antigens